1. Field of the Invention
The present invention relates generally to the field of automatic sanding devices, and more specifically to an electric sanding apparatus having multiple abrasive flaps.
2. Description of the Prior Art
There has long been a need for a portable, lightweight, automatic sanding tool to replace manual sanding of doors, jambs, casings, louvered bifolds, shutters and the like, having unfinished surfaces which need sanding after priming or sealing, or having previously painted surfaces which need sanding before application of finish coats of paint. Furthermore, there has long been a need for a sanding element which can uniformly sand uneven walls and other surfaces and sand between projections on surfaces.
A variety of automatic sanding devices and elements is found in the prior art. One such device is taught in Taafe, U.S. Pat. No. 3,498,009, issued Mar. 3, 1970. Taafe discloses a cylindrical sanding element and element rotating device, resembling a paper towel rack with a motor and handle on it. A problem with Taafe is that its broad uniform sanding element would only make contact with the high points of an uneven surface. Recessed areas would thus remain unsanded. Also, the reach of Taafe is only a few inches beyond its handle, making Taafe unsuited for reaching high or otherwise hard to reach areas.
A finishing wheel or element is disclosed in Schaffner, U.S. Pat. No. 3,706,167, issued Dec. 19, 1972. Schaffner comprises an annulus of flaps bonded near the center to form a substantially solid hub. This hub is mounted on any of several rotary tools. Narrow Schaffner flaps would effectively sand between projections and within valleys of surface undulations. Yet they would also cover only a small surface area at a given moment, making the sanding job very time-consuming. On the other hand, wide Schaffner flaps would be unable to reach between surface peaks, as in Taafe. Therefore, Schaffner is either excessively slow or simply unsuited to sanding uneven surfaces.
Hasegawa, U.S. Pat. No. 3,795,498, issued Mar. 5, 1974, teaches a method of making a sanding wheel from a stack of abrasive, flexible leaves. Grooves are cut in the edges of the stack. An adhesive-covered string is inserted into these grooves and the leaves are then radially wrapped around a hub. Hasegawa is simply the wide flap version of Schaffner, and is thus unsuited to evenly sanding undulating surfaces.
Ali, U.S. Pat. No. 3,872,630, issued Mar. 25, 1975, is another variation of radially-mounted flaps on a hub. Ali provides a means of inserting clusters of flaps, fastened together face-to-face at one end, into a specially slotted hub portion. The problems of Ali when applied to undulating surfaces are identical to those of Schaffner and Hasegawa. The same is true of Wilson, U.S. Pat. No. 4,365,448, issued Dec. 28, 1982 and of Block, U.S. Pat. No. 4,872,292, issued Oct. 10, 1989.
It is thus an object of the present invention to provide a sanding element which can evenly and rapidly sand undulating surfaces and surfaces having projecting portions.
It is another object of the present invention to provide a sanding apparatus which is light and easy to handle.
It is still another object of the present invention to provide a sanding apparatus and sanding element to the skilled tradesman as well as to the ordinary do-it-yourselfer, which effectively sands planar as well as irregular surfaces quickly, efficiently, at low cost and with minimal labor.
It is finally an object of the present invention to provide such a sanding apparatus and sanding element which are relatively inexpensive, simple in construction and sufficiently compact to permit easy transport and storage.